The Pimsleur language instruction CDs use a similar method of spaced repetition. At least for me, it was incredibly effective.
I have been using the Pimsleur Spanish CDs for almost 6 months. I have made a lot of progress (especially with vocabulary) but am still at a beginner level (high beginner though, almost low intermediate).
I am still amazed of how "organic" was the learning.. I mean, after some time I just started "understanding" more advanced conversations to the point that even my chinese friends got startled.
Also, I have not used the CD's for over 3 years (or spend time in china) and I still recall most of what I learned.